Investigators with the Tallahassee Police Department are seeking tips from anyone who might have encountered Florida State University professor Daniel Markel before he was found shot in the head at his home this month.

In a Monday news release, authorities asked anyone to come forward who might have seen Markel in specific areas, mostly on the north end of the city, but also near the centrally located FSU law school where he taught.

A department spokesman didn't comment on why authorities are looking into those particular areas.

Police went to the professor's home on July 18 after receiving a call from Markel's neighbor, who told officers he heard a loud bang before seeing a vehicle drive away from his house.

When he went to investigate, he found his neighbor inside his garage, in the driver's seat of his car, bleeding and in a daze. The driver's side window of the car had been bashed open, the report says.

A heavily redacted police report released Friday states there was no sign of forced entry, which Tallahassee police spokesman David Northway said could mean Markel knew the shooter. The report does not state whether the garage door was open.

Also in the report, the neighbor told police a white or silver vehicle left the home, describing it as a Toyota Prius, or a Prius "type" of vehicle.

Police on Wednesday released via social media a picture of a silver car they called a "vehicle of interest." Police on Facebook cautioned it may have been a resident, passerby or delivery driver.

Northway told CNN that investigators used a nearby business' surveillance camera to capture an image of what appears to be a Prius.

Police say there were no signs of a robbery and have yet to disclose a possible motive. They have been following up on more than 50 leads and offered a $3,000 reward for information leading to an arrest.

In a news release Friday, Tallahassee Police Chief Michael J. DeLeo said, "Our investigators are using all resources available to them and are continuing to explore all of the tips that we have received."

Police have been in contact with Markel's former wife, Wendi Adelson, also an FSU law professor, said her attorney, Jimmy Judkins.

She is "scared to death" that the killer may be targeting her entire family, said Allen Grossman, a close family friend, who has known Markel and Adelson for several years. The couple had two sons together.

Last week, Judkins told CNN his client has no idea why this happened.

Markel began working at FSU in 2005 after receiving his bachelor's degree at Harvard College, a master's from the University of Cambridge and a law degree from Harvard. During his FSU tenure, the Toronto native taught several classes and wrote extensively about criminal law, including articles published in the Yale Law Review, among others.

Markel also founded PrawfsBlawg, a blog focused on law and life, and his writing appeared in publications such as The New York Times, Slate, The Jerusalem Post and The Atlantic Monthly. On PrawfsBlawg, 10 fellow law professors posted about the respect they had for Markel and the mutual love he shared with his friends and family.

"His boundless energy was at the center of this community; it made it run, it gave it life. We are stunned and bereaved by his loss, and our thoughts go to his two little boys, who were precious to him, and to his family."